Apparatus for replicating ice crystals

ABSTRACT

A device for replicating ice crystals or water droplets which comprises a housing enclosing a cavity in which is mounted an electrical heating element suitably connected to a power source. The resistance wire on the element is coated with the monomer, methyl 2-cyanoacrylate, which when heated vaporizes filling the cavity. Ice crystals or water droplets falling through the vapor are coated with the monomer as they drop to the bottom of the container. The coated droplets or crystals are dehydrated leaving replicas which can be viewed through a microscope.

United States Patent [72] inventors Frederick R. Odencrantz [56]References Cited Chin- Lakeg UNITED STATES PATENTS 'F Cam-1 2,872,3412/1959 Stein 118/49.l x 3 128 205 4/1964 lllsley 118/49 121 App]. No.869,525 [22] Fil d O t, 27, 1969 Primary Examiner.l. V Truhe [45]Patented June 8, 1971 Assistant Examiner-C. L. Albritton [73 A i Th U id sum f America as Att0rneys-R. S. Sciascia and Roy Miller representedby the Secretary of the Navy ABSTRACT: A device for replicating icecrystals or water droplets which comprises a housing enclosing a cavityin which is mounted an electrical heating element suitably con- [54] E?P RFFEPuCAnNG CRYSTALS nected to a power source. The resistance wire onthe element a is coated with the monomer, methyl 2-cyanoacrylate, which[52] US. Cl H 219/271, when heated vaporizes filling the cavity. icecrystals or water 219/275 droplets falling through the vapor are coatedwith the [51] lnt.Cl F22b 1/28 monomer as they drop to the bottom of thecontainer. The [50] Field of Search 219/271, coated droplets or crystalsare dehydrated leaving replicas which can be viewed through amicroscope.

Pmmmm 8|9Ii 3584.191

INVENTO FREDERICK K. ODENCR 2 LEE E. HUMISTON PETER H. HILDEBRAND ROYMILLER APPARATUS FOR REPLICATING ICE CRYSTALS GOV ERNM ENT INTEREST Theinvention described herein may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to a method andapparatus for replicating ice crystals and water droplets.

In the field of weather modification investigation of the growth ofwater droplets and ice crystals under varying conditions has provided agreat deal of information on the ice crystal growth mechanism, thedistribution of charges on the crystal surfaces, and atmosphericprocesses such as crystal clustering, and ice crystal multiplicationtechniques. Nakaga in Compendum of Meteorology, American MeteorologySociety, Boston, (I954), and l-Iallet and Mason in the Proceedings ofthe Royal Society;" London, Ser. A, 247, 440 1958) observed the icecrystal habit dependence on temperature; Vonnegut in GE. ResearchLaboratory Project Cirrus," Report No. (1948), Schaefer in ChemicalRevue," page 44 (1949), and others have reported on the effects of vaporcontaminants in the atmosphere on the crystal habit. The present deviceis a simple means for replicating ice crystals and waterdroplets usefulin the field of weather modification.

It is therefore an object of the present invention to provide a simplemethod and apparatus for preserving in detail the features of icecrystals and water droplets for use in the study of air andwaterproblems.

DESCRIPTION OF THE DRAWING FIG. I in partial section illustrates oneembodiment of the present invention;

FIG. 2 is an isometric of another embodiment of the invention;

FIG. 3 section of the face of FIG. 2; and

FIG. 4 is an exploded view of the coated resistance wire used in bothembodiments.

BRIEF DESCRIPTION OF THE INVENTION Referring now to the drawing there isshown in FIG. 1 an embodiment of the present invention which comprises acylindrical housing 11 having walls about one-half inch thick. The wallsenclose a cavity or cloud chamber 17. A metal collar 14 fits into recess16 which is formed on the top edge of housing 11. Collar 14 may bewelded to the housing wall or molded as a part of the housing preform. Aheating element comprising a resistance wire coated with methyl2-cyanoacrylate 26 is mounted on the inner'wall of collar 14, andconnected by leads 18 to a suitable power source, in this instance, al-l volt battery (not shown). The wire used was the nickelchromiumalloy, Nichrome, but other wire generally used in heating elements suchas Chromel, Tophet, copper, etc., is suitable. Cavity 17 is closed bymeans of a metal disc 19 which moves around steel pin 20 positioned onthe top edge of collar 14. A movable circular plate 12 forms the base ofhousing 11. Plate 12 is easily removed. A groove 13 is provided aroundthe perimeter of plate 12 and is of dimensions such as to closely engagethe bottom edge of said housing 11. A bore is provided monomer isallowed to deposit on the ice crystals or water droplets for about 30seconds. The plate on which the coated crystals or droplets aredeposited is now carefully removed and stored in a cold desiccator untildehydrated. The film forming the surface of the crystals is thin andfragile so caremust be taken to allow a gradual change of pressure ifthe samples are placed in a vacuum system such as might occur if placedon the viewing stage of an electron microscope. The dehydrated samplesshould be placed in a closed container. In the presence of water thethin films may deteriorate and do deteriorate rapidly in the presence ofcertain organic vapors.

There is shown in FIG. 2 another embodiment of this invention which isfairly rugged and is used in the field. It comprises a metal housing 22,having a bore 23 extending through one end. Bore 23 is closed on thebackside 24 of housing 22 by means of a heating unit designated 25 whichis suitably connected by leads 34 to a power source connected at 33. Theunit is provided with resistance wire 15 coated with methyl 2-cyanoacrylate 26 illustrated in FIG. 4. Heating unit 25 extends aboutmidway into bore 23 which is closed on the front face 27 of housing 22by a shutter 28 illustrated in FIG. 3. Shutter 28 is moved when spring31 is actuated by a turn of knob 29 which is mounted on shaft 30positioned on the backside 24 of housing 22. Knob 29 also fits over amicroswitch 32 and movement of the knob initiates the power source at 33and at the same time causes opening of shutter 28. Actuation of thepower source at 33 causes wire 15 to heat up sufficiently to vaporizethe monomer coating 26. In operation this device is placed face downover a substrate on which water droplets or ice crystals are deposited.The shutter is opened and the vapor which is created by the simultaneousheating of the coated wire forms a film on the droplets which are thenslowly dehydrated leaving replicas. A 15 to 20 second exposure issufficient to coat the ice crystals or droplets with enough monomer thatareas with high curvature maintain their shape after evaporation of thewater. For replication of larger areas it is necessary to deposit aheavier coating of the monomer.

Replicas made by this invention may be viewed with dark field or phasecontrast illumination if glass slides are used as a substrate, or arepositioned on the bottom of the replicating device. If the sample is tobe examined by a scanning microscope, the replica is prepared on a metalslide or substrate and then coated with a gold or gold-palladium film.

The coated wire or filament for this device was constructed from 0.05cm. diameter resistance Nichrome wire. The cold resistance of the wireis approximately 0.04 ohms/cm. The grid or framework is formed so asupply of the liquid monomer, methyl Z-cyanoacrylate, is maintained inthe sharp bends of the wire as shown in FIG. 4. A single loading of 50to mg. of the monomer is sufficient for several replications. A 1.5 voltdry cell battery with an external 0.5 ohm resistor is suitable for thepower supply. The monomer used herein is relatively stable in theabsence of water. The temperature of the replicator should be stabilizedbefore use and it should be stored in a thermally insulated carrierafter use.

What we claim is:

l. A device for replicating water droplets and ice crystals comprising:

a housing enclosing a cavity for receiving ice crystals and waterdroplets, provided with at least one movable closure means;

a resistance wire coated with methyl Z-cyanoacrylate mounted within saidcavity; and

a power source positioned outside said cavity to which said coated wireis suitably connected;

whereby actuation of the power source causes heating of the wire therebygenerating a cloud of methyl 2- cyanoacrylate which coats said dropletsand crystals as they come in contact with the methyl Z-cyanoacrylate.

2. The device in accordance with claim 1 wherein said housing isprovided with two movable closure means whereby said crystals anddroplets can enter at one side and be removed from the other side.

2. The device in accordance with claim 1 wherein said housing isprovided with two movable closure means whereby said crystals anddroplets can enter at one side and be removed from the other side.